TROPICAL BIOLOGY AND CONSERVATION MANAGEMENT – Vol. IV - Epiphytes - Fernanda Reinert and Talita Fontoura
EPIPHYTES
Fernanda Reinert and Talita Fontoura
Universidade Federal do Rio de Janeiro, Brazil, Departamento de Botânica.
Universidade Estadual de Santa Cruz, Departamento de Ciências Biológicas, Bahia,
Brazil.
Keywords: canopy, lichens, ferns, bromeliads, orchids, CAM, holo-epiphytes, hemiepiphytes, poikilohydrous, homoiohydrous, phorophyte, Atlantic Forest, habitat
fragmentation, Paleotropical forests, Neotropical forests.
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Contents
1. Introduction
2. Geographic, regional, and point scales
3. Photosynthesis
4. Water relations
5. Mineral Nutrition
6. Lichens
7. Ferns
8. Orchids
9. Bromeliads
10. Habitat modification: the forest loss
11. Conclusion
Acknowledgements
Glossary
Bibliography
Biographical Sketches
Summary
Epiphytes are organisms that grow upon a living plant for support and are not parasites;
they are usually independent of the host plant for water and nutrition. Epiphytism is
present among many groups, such as fungi, algae and plants, and in associations such as
the lichens. They comprise about 10% of vascular plants and are particularly abundant
and diverse in the wet tropics. Epiphytes are part of the canopy community and can be
of major importance for nutrient cycling of forests and are important for creating niche
habitats for several animal species. Different morphological and physiological
adaptations were necessary to conquer the epiphytic habit, many related to water
economy. Epiphytes can be classified according to their dependence on the supportive
tree; growth habit; water economy mechanisms, amongst others; and usually, the wetter
the forest, the larger the number of epiphytes. Altitude also influences their abundance
and richness. Other factors are also very important in explaining their diversity and the
size of the supporting tree and the texture of the bark have a role to play. Epiphytes,
among other canopy life forms are especially vulnerable to extinction because
endemism is relatively frequent and the rate of deforestation scarily high. This chapter
is dedicated to the biology of epiphytes; we introduce their diversity and discuss aspects
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TROPICAL BIOLOGY AND CONSERVATION MANAGEMENT – Vol. IV - Epiphytes - Fernanda Reinert and Talita Fontoura
of their nutrition, photosynthesis and water relationships. The following groups received
special attention: lichens, ferns, and two seed families, Orchidaceae and Bromeliaceae.
1. Introduction
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The term epiphyte, from the Greek epi (upon) and phyton (plant), was first introduced
by Mirbel in his book Èlements de physiologie végétale et de botanique (1815) and
refers to an organism that grows upon a living plant for support. Epiphytes are not
parasites, i.e. they are usually independent of the host plant for nutrition, although they
may sometimes damage the host plant, often by shading. Also, they are not restricted to
grow on a host plant, for instance, epiphytes can be found growing on wires (Figure 1).
There are holo-epiphytes, which complete their life cycle without contact with the
ground and the hemi-epiphytes, which, at some stage of their development, root in
ground soil. Orchids are probably the most famous representative of holo-epiphytes and
the stranglers Ficus are well known hemi-epiphytes. Field surveys may adopt wider
classifications including accidental, facultative, hemi-epiphytes, true epiphytes, and
parasites in the category “epiphytes” or narrower classifications including only
facultative and true epiphytes in the list of the epiphytic species occurring in a given
region.
Figure 1. Epiphytes, Tillandsia stricta and T. tricholepis (Bromeliaceae), growing on
wires in the city of Rio de Janeiro
Epiphytism is considered a paraphyletic trait present among all large groups, such as
bacteria, fungi, plants, and in associations such as the lichens. Epiphytes are extremely
common among aquatic species growing on algae or on aquatic flowering plants.
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TROPICAL BIOLOGY AND CONSERVATION MANAGEMENT – Vol. IV - Epiphytes - Fernanda Reinert and Talita Fontoura
Vascular and non-vascular epiphytes biomass production in many rain forest canopies is
significant, especially in cloud forests. Among vascular plants, epiphytes comprise
about 10% distributed among 84 families with over 25,000 species and they are
particularly abundant in the wet tropics.
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Epiphytes may occur from the basis of tree trunks up to the tree crowns on trees as high
as 50m or even taller. These plants were observed and studied by naturalists since the
19th century, beginning with SCHIMPER in Central America, then in the 1940’s with
priest RAMBO in the sub-tropical forest from south Brazil and in the 1960’s with
HOSOKAWA in the forests of Micronesia. Nevertheless, regular studies of epiphytes in
the tree crowns were improved recently by climbing techniques called “single rope
techniques” consisting on rock climbing techniques adapted to peculiarities of climbing
trees.
Because epiphytes are mostly found in the tree crowns, these plants are part of the
canopy community where the full diversity of organisms remains to be mapped. Even
though studies on the epiphytic community have begun two hundred years ago, the bulk
of studies on epiphytes started on the 1980´s as a result of scientific studies developed
in the forest canopy favoring the discussion of canopy access, ecological role,
ecophysiology and conservation of epiphytes. Thus, in some tropical areas, the organic
matter released by epiphytes is the most important flux of nutrients reaching the forest
floor. Besides participating on the nutrient cycling of forests, these plants may increase
the structural complexity of forests because of the frequently dependent fauna
associated to these plants. For instance, DUELLMAN & PIANKA (1990) suggested
that the diversity of frogs is larger in the Neotropics, partially because of the presence of
bromeliads, which have a large number of epiphytic species. These plants would be
responsible to the availability of abundant and diverse microhabitats for these
vertebrates.
Epiphytes usually obtain water and nutrients from fog, dew, rainwater and through fall.
Water availability for epiphytic plants is irregular and plants tend to endure drought
stress between precipitation events, even in everwet regions. Dry periods are
particularly crucial for juvenile plants and are a primary cause of death among them.
Different morphological and physiological adaptations were necessary to conquer the
epiphytic habit. For instance, some species of orchids have bulbs, some species of
pteridophytes loose their leaves in unfavorable periods of dryness, and many bromeliad
species have superimposed leaves in a rosulate shape which withhold water and debris.
Some orchids have a strong leaf reduction keeping their roots as the only organ to
maintain the photosynthesis. Some other species are temporarily epiphytes because their
development is composed by an initial phase on the tree top, an intermediate phase as
hemi-epiphyte with roots growing down to the forest floor, and a final phase as a mature
tree. This is the case of some Ficus which usually kill their host tree, reason why they
are called “strangler trees”.
The variety of morphological and physiological adaptations and relationship with their
supportive trees enabled different classification systems, resumed by BENZING (1990):
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TROPICAL BIOLOGY AND CONSERVATION MANAGEMENT – Vol. IV - Epiphytes - Fernanda Reinert and Talita Fontoura
I – RELATIONSHIP TO THE SUPPORTIVE TREE
A. Autotrophs (plants supported mechanically by woody vegetation; no nutrient
extracted from vasculature of phorophytes)
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1. Accidental (predominantly terrestrial plants that accidentally germinate in the
tree trunk crevices, e.g. Kalanchoe spp.)
2. Facultative (species that may grow either on the tree top or on the forest floor,
e.g. species of sub-family Bromelioideae of Bromeliaceae; Figure 2)
Figure 2. Facultative epiphytes: A- Nidularium bicolor (Bromeliaceae) on tree trunk; Bthe same species as terrestrial a few meters away from the epiphytic individuals.
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TROPICAL BIOLOGY AND CONSERVATION MANAGEMENT – Vol. IV - Epiphytes - Fernanda Reinert and Talita Fontoura
3. Hemiepiphytic
ƒ
Primary (germination occurs in the tree top but the development of roots
and stems occur down to the forest floor)
a. Strangling (the stem becomes lignified around the supportive
tree becoming a erect trunk. In this situation, the hemiepiphyte
crown may overtop the supportive tree; Figure 3)
b. Nonstrangling (e.g., Clusia species)
Secondary (germination occurs on the forest floor but the development
of roots and stems occurs upward the supportive tree)
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ƒ
4. “Truly” epiphytes (the “holo-epiphytes” of Schimper; Figure 4)
B. Heterotrophs (plants subsisting on xylem contents of their supportive trees)
1. Parasites (also called “mistletoes”, e.g. species of Viscaceae and Loganiaceae
families)
Figure 3. Primary hemiepiphyte: A Ficus sp. tree (Moraceae). Note that the
hemiepiphyte trunk enfolded the phorophyte and letft a few gaps from where one can
see the dead tree.
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TROPICAL BIOLOGY AND CONSERVATION MANAGEMENT – Vol. IV - Epiphytes - Fernanda Reinert and Talita Fontoura
Figure 4. True epiphytes: Orchidaceae on the tree branch of Lecythis pysonis
(Lecythidaceae).
Figure 5. Herbaceous rosulated bromeliad: this leaf arrangement is characteristic of
many Bromeliaceae species as this Guzmania sp.. Note water and debris impounded b
the leaves.
II. GROWTH HABIT
A. Trees
B. Shrubs
C. Suffrutescent to herbaceous forms
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TROPICAL BIOLOGY AND CONSERVATION MANAGEMENT – Vol. IV - Epiphytes - Fernanda Reinert and Talita Fontoura
1. Tuberous
a. Storage: woody and herbaceous
b. Myrmecophytic (plants associated to ants): mostly herbaceous
2. Broadly creeping: woody or herbaceous
3. Narrowly creeping: mostly herbaceous
4. Rosulate (Figure 5): herbaceous
5. Root/leaf tangle: herbaceous
6. Trash-basket: herbaceous
III. WATER BALANCE MECHANISMS
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A. Poikilohydrous (many bryophytes, some pteridophytes and a few angiosperms)
B. Homoiohydrous
1. Hygrophytes
2. Mesophytes
3. Xerophytes
a. Grought-endurers
b. Drought-avoiders
4. Impounders
IV. LIGHT REQUIREMENTS
A. Exposure types (largely exposed to sites in full or nearly full sun; Figure 6)
B. Sun types (tolerant to medium shade)
C. Shade-tolerant types (tolerant to deep shade)
Figure 6. The bromeliad “spanish moss” (Tillandsia usneoides) on the external branches
of trees, growing as exposed epiphytes.
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TROPICAL BIOLOGY AND CONSERVATION MANAGEMENT – Vol. IV - Epiphytes - Fernanda Reinert and Talita Fontoura
V. SUBSTRATE REQUIREMENT
A. Relatively independent of root medium (obtain moisture and nutrition primarily from
rain, mist and dew)
1. Mist and atmospheric forms (with minimal attachment to bark)
2. Twig/bark inhabitants
3. Species that create substitute soils or attract ant colonies (ant house epiphytes)
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B. Tending to utilize a specific type of root medium for moisture and nutrition)
1. Humus-adapted
a. Generalist types (root in shallow humus mats)
b. Deep humus types (penetrate in trees knotholes or rooting wood)
c. Ant-nest garden and plant-catchment inhabitants (e.g., Platycerium spp., Utricularia
humboltii)
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Bibliography
Ahmadjian V. (1995). Lichens are more important than you think. BioScience 45:124. [This one-page paper
makes the point of how important lichens are with some important statistics.]
Benner J.W. Vitousek P.M. (2007). Development of a diverse epiphyte community in response to phosphorus
fertilization. Ecology Letters 10(7): 628-636. [This is a case study reporting the response of an epiphytic
community to several nutrients, such as nitrogen and phosphorous.]
Benzing, D. H. (1990). Vascular epiphytes. General biology and related biota, 354 pp. Cambridge University
Press: Cambridge UK. [This is one of the most comprehensive works on epiphytes.]
Colwell, R. K. and Lees, D. C. (2000). The mid-domain effect: geometric constraints on the geography of
species richness. Trends in Ecology and Evolution 15: 70-76. [This article provides a deep and clear
explanation of why different organisms have so many species in the mid elevations. In this case “deep” does
not mean an encrypted text and many readers may follow all concepts behind mid-domain effect.]
Duellman, W. E. & Pianka, E. R. (1990). Biogeography of nocturnal insectivores: historical events and
ecological filters. Annual Review of Ecology and Systematics 21:57-68. [The authors explore in which extent
the historical events and ecological constraints are responsible for lizard and anuran biogeography in Old
World and New World tropical forests. The presence of bromeliads is mentioned as one of the main factors to
influence the high diversity of anuran in the Neotropics.]
Gradstein, S. R.; Nadkarni, N. M.; Krömer, T.; Holz, I.; Nöske, N. (2003). A protocol for rapid and
representative sampling of vascular and non-vascular epiphyte diversity of tropical rain forests. Selbyana 24:
105-111. [This article provides a standardized protocol to enable inventory of epiphytes in different tropical
©Encyclopedia of Life Support Systems (EOLSS)
TROPICAL BIOLOGY AND CONSERVATION MANAGEMENT – Vol. IV - Epiphytes - Fernanda Reinert and Talita Fontoura
rain forests using the same field methodology. Although it is not intended to provide species lists of different
localities, the protocol may be very useful to conservationist purposes which need quick answers based on
species number and comparisons of different localities.]
Hawksworth D.H. (1988). The variety of fungal-algal symbioses, their evolutionary significance, and the
nature of lichens. Botanical Journal of the Linnean Society 96:3-20. [This is an overview about the evolution
and symbiotic nature of lichens.]
Hietz P., Briones O. (2001). Photosynthesis, chlorophyll fluorescence and within-canopy distribution of
epiphytic ferns in a Mexican cloud forest. Plant Biology (Stuttgart) 3: 279-287. [This is a case study on the
different aspects of fern’s photosynthesis under natural conditions.]
Hietz, P., Wanek, W., Wania, R., Nadkarni, N.M. (2002). Nitrogen-15 natural abundance in a montane cloud
forest canopy as an indicator of nitrogen cycling and epiphyte nutrition. Oecologia 131(3):350-355. [This is a
case study using nitrogen stable isotopes to infer about the nutrition of epiphytes and how they influence
nitrogen cycling.]
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Hofstede, R.G.M, Wolf, J.H.D. (1993). Epiphytic biomass and nutrient status of a Colombian upper montane
rain forest. Selbyana 4: 37-45. [This is a case study which attempts to quantify the entire biomass of epiphytes
on a single phorophyte.]
Johansson, D. R. (1974). Ecology of vascular epiphytes in West African rain forest. Acta Phytogeographica
Suecica 59: 1-136.[This is a classical article which is the basic literature to all those who intend to know more
about epiphytes. Johansson developed his detailed work in Africa using a lot of field experience and simple
analysis of natural history of epiphytic plants.]
Reich A., Ewel J.J., Nadkarni N.M., Dawson T. Evans R.D. (2003). Nitrogen isotope ratios shift with plant
size in tropical bromeliads. Oecologia 137(4):587-590. [The authors use nitrogen natural abundance signature
in bromeliads to investigate shifts in the nitrogen composition according to size.]
Watkins J.E. Jr, Rundel P.W., Cardelús C.L. (2007). The influence of life form on carbon and nitrogen
relationships in tropical rainforest ferns. Oecologia 153(2): 225-232. [This work investigates carbon and
nitrogen relations in epiphytes, hemi-epiphytes and soil-rooted ferns.]
Wolf, J. H. D and Connings, C. J. F. (2001). Towards the sustainable harvesting of epiphytic bromeliads: a
pilot study from the highlands of Chiapas, Mexico. Biological Conservation 101:23-31.[This article deals with
population ecology of epiphytic species, nevertheless, its final approach of species management is the starting
point to applied ecology where authors suggest effective actions to diminish overexploitation of epiphytic
species. Further improvements are probably necessary but this is the first step to real conservationist actions.]
Zotz, G. & Winter, K. (1994). Annual carbon balance and nitrogen-use efficiency in tropical C3 and CAM
epiphytes. New Phytol. 126: 481-492. [A comprehensive study comparing the balance of carbon and nitrogen
in epiphytes with C3 and CAM photosynthesis.]
Biographical Sketches
Fernanda Reinert received her Bachelor degree in Biology-Ecology at the Universidade Federal do Rio
de Janeiro (UFRJ) in 1989. Her PhD was done at the University of Newcastle upon Tyne in the UK under
the supervision of Dr. Howard Griffiths in 1995. Since 1998, she has been an associate professor at
UFRJ. Her areas of interest are: photosynthesis under stress, the crassulacean acid metabolism (CAM),
epiphytes, Bromeliaceae, and stable isotopes. She was the director of a post graduation program in Plant
Biotechnology from 2001-2005.
Talita Fontoura received her Bachelor degree in Biology at the Universidade Santa Úrsula (USU) in
1988. Her PhD in Ecology was done at the Universidade Estadual de Campinas (UNICAMP) under the
supervision of Dr. Flavio A. M. dos Santos in 2005. Since 1996, she has been associate professor at the
Universidade Estadual de Santa Cruz (UESC). Her areas of interest are: Bromeliaceae, epiphytes, canopy,
Atlantic Rainforest and structure of vegetation.
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